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A description of the origin of humanity

Map of early diversification of modern humans according to mitochondrial population genetics see: The first lineage to branch off from Mitochondrial Eve is L0.

  • Once a sperm merges with an egg, all the sperm mitochondria are destroyed;
  • It has also been shown that high-altitude adaptation in Tibetans may be a consequence of archaic Denisovan DNA sequence in a region of DNA associated with haemoglobin concentration at high altitudes.

It is also found among the Mbuti people. The macro haplogroups M and Nwhich are the lineages of the rest of the world outside Africa, descend from L3.

  • Isolated proponents of polygenism held forth in the mid-20th century, such as Carleton Coon , who thought as late as 1962 that H;
  • It is now known that homologous features can be generated from entirely different gene segments within different unrelated species.

L3 is about 84,000 years old and haplogroup M and N are about 63,000 years old. If there had been several migrations, one would expect descendants of more than one lineage to be found. L3's female descendants, the M and N haplogroup lineages, are found in very low frequencies in Africa although haplogroup M1 populations are very ancient and diversified in North and North-east Africa and appear to be more recent arrivals.

A possible explanation is that these mutations occurred in East Africa shortly before the exodus and became the dominant haplogroups after the departure through the founder effect.

Recent African origin of modern humans

Alternatively, the mutations may have arisen shortly afterwards. Southern Route and haplogroups M and N[ edit ] Results from mtDNA collected from aboriginal Malaysians called Orang Asli and the creation of a phylogenetic tree indicate that the hapologroups M and N share characteristics with original African groups from approximately 85,000 years ago and share characteristics with sub-haplogroups among coastal south-east Asian regions, such as Australasia, the Indian subcontinent and throughout continental Asia, which had dispersed and separated from its African origins approximately 65,000 years ago.

Human evolution

This southern coastal dispersion would have occurred before the dispersion through the Levant approximately 45,000 years ago. Evidence of the coastal migration is thought to have been destroyed by the rise in sea levels during the Holocene epoch. The group that crossed the Red Sea travelled along the coastal route around Arabia and Persia until reaching India. The indigenous people of the Andaman Islands also belong to the M lineage. The Andamanese are thought to be offshoots of some of the earliest inhabitants in Asia because of their long isolation from the mainland.

They are evidence of the coastal route of early settlers that extends from India to Thailand and Indonesia all the way to Papua New Guinea. The proportion of haplogroup M increases eastwards from Arabia to India; in eastern India, M outnumbers N by a ratio of 3: Crossing into Southeast Asia, haplogroup N mostly in the form of derivatives of its R subclade reappears as the predominant lineage.

Human genetic variation and Human genetic clustering A 2002 study of African, European and Asian populations, found greater genetic diversity among Africans than among Eurasians, and that genetic diversity among Eurasians is largely a subset of that among Africans, supporting the out a description of the origin of humanity Africa model.

Based on this evidence, the study concluded that human populations encountered novel selective pressures as they expanded out of Africa. According to this study, Papua New Guineans continued to be exposed to selection for dark skin color so that, although these groups are distinct from Africans in other places, the allele for dark skin color shared by contemporary Africans, Andamanese and New Guineans is an archaism.

A 2014 study by Gurdasani et al. For this reason, JCV has been used as a genetic marker for human evolution and migration.

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From this Shackelton et al. Admixture of archaic and modern humans[ edit ] Main article: Archaic human admixture with modern humans Evidence for archaic human species descended from Homo heidelbergensis having interbred with modern humans outside of Africa, was discovered in the 2010s.

This concerns primarily Neanderthal admixture in all modern populations except for Sub-Saharan Africans but evidence has also been presented for Denisova hominin admixture in Australasia i.

AterianBaradostianand Microlith In addition to genetic analysis, Petraglia et al. He proposed that the stone tools could be dated to 35 ka in South Asia, and the new technology might be influenced by environmental change and population pressure.

Human origins

The cladistic relationship of humans with the African apes was suggested by Charles Darwin after studying the behaviour of African apesone of which was displayed at the London Zoo. Haeckel argued that humans were more closely related to the primates of South-east Asia and rejected Darwin's African hypothesis.

In each great region of the world the living mammals are closely related to the extinct species of the same region. It is, therefore, probable that Africa was formerly inhabited by extinct apes closely allied to the gorilla and chimpanzee ; and as these two species are now man's nearest allies, it is somewhat more probable that our early progenitors lived on the African continent than elsewhere.

But it is useless to speculate on this subject, for an ape nearly as large as a man, namely the Dryopithecus of Lartet, which was closely allied to the anthropomorphous Hylobatesexisted in Europe during the Upper Miocene period; and since so remote a period the earth has certainly undergone many great revolutions, and there has been ample time for migration on the largest scale.

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Almost fifty years later, Darwin's speculation was supported when anthropologists began finding fossils of ancient small-brained hominins in several areas of Africa list of hominina fossils. The hypothesis of recent as opposed to archaic African origin developed in the 20th century.

The "Recent African origin" of modern humans means "single origin" monogenism and has been used in various contexts as an antonym to polygenism. The debate in anthropology had swung in favour of monogenism by the mid-20th century.

Isolated proponents of polygenism held forth in the mid-20th century, such as Carleton Coonwho thought as late as 1962 that H. Multiregional origin of modern humans The historical alternative to the recent origin model is the multiregional origin of modern humansinitially proposed by Milford Wolpoff in the 1980s.

This view proposes that the derivation of anatomically modern human populations from H. The hypothesis necessarily rejects the assumption of an infertility barrier between ancient Eurasian and African populations of Homo. The hypothesis was controversially debated during the late 1980s and the 1990s. Cann and Mark Stoneking worked on genetic dating of the matrilineal most recent common ancestor of modern human populations dubbed " Mitochondrial Eve ".

To identify informative genetic markers for tracking human evolutionary history, Wilson concentrated on mitochondrial DNA mtDNApassed from mother to child. This DNA material mutates quickly, making it easy to plot changes over relatively short times.

Evolution Of Man

With his discovery that human mtDNA is genetically much less diverse than chimpanzee mtDNA, Wilson concluded that modern human populations had diverged recently from a single population while older human species such as Neanderthals and Homo erectus had become extinct.

By 1999, estimates ranged around 150,000 years for the mt-MRCA and 60,000 to 70,000 years for the migration out of Africa. A reanalysis on LM3 and other ancient specimens from the area published in 2016, showed it to be akin to modern Aboriginal Australian sequences, inconsistent with the results of the earlier study.